Transparent plastic cases have traditionally been in popular use as containers for recording media such as CDs, CD-ROMs and DVDs for use with computers, recording music or other purposes. This kind of case typically comprises a lid and a bottom, on which the object such as a music CD is placed. The lid is opened when the CD kept therein is to be taken out. When an object such as a CD is shipped from its vendor, it comes with a label made of paper or some other material bearing the title, table of contents, and other relevant information and which is placed together with it in the case. The part of the label which fits with the spine of the case serves as an identifier, as the spine of a book would be, particularly when the case is placed upright together with a number of similar cases in a case holder. The designing, printing, and fitting of the label, which usually involves a certain amount of waste, also entails a considerable cost.
As an attempt to improve the printing procedure for such labels, Japanese Patent Laid-Open No. 8-11412 discloses a spine printing apparatus and a spine formation tool, but this pertains only to a technique to increase printing precision, rather than a way of eliminating the need for printing and fitting.
For a recording medium such as a CD that is not sold in a case with a label, the user needs to buy a universal transparent plastic case to keep or carry it. Since the spine of such a universal case bears no label indicating its contents and therefore the recording medium cannot be seen from the side of the case, it is time-consuming to locate any given recording medium among a number of similar items.
Even if a spine label is provided, it may be difficult to write on since the case is usually less than 10 mm in thickness.
Even where a spine label is provided, when the recording medium taken out of its case is to be stored again, the user may put it into a wrong case by mistake. As a result, the spine label on the case may not match the recording medium inside. It is thus a chore to ensure that every recording medium is always kept in the right case.
On the other hand, as a technique for indicating the contents of the case, for instance, U.S. Pat. No. 4,863,026 discloses a keeping case for use with information recording devices. This technique features a Fresnel lens built into the lid of the case, such that the lens magnifies the index card within the case. As similar techniques for displaying the contents through the lid of the case, National Publication of International Patent Application No. 9-511203 discloses a flat box device equipped with a multiple-view lens, and National Publication of International Patent Application No. 11-510129 discloses an indication system using a multiple-visual-angle optical element. According to these techniques, a number of miniature planoconvex lenses are provided in the lid of the case, and text and images are printed in an interlacing manner on the surface of the album card to be inserted into the back of the lid. This arrangement enables the text and images on the label to be presented to the viewer in a variety of ways depending on the angle at which the viewer sees them.
Another technique for indicating the contents of a case pertains to a cosmetic container provided with an integrated lens structure disclosed in U.S. Pat. No. 4,044,889. By this technique, a list of contents and the like written inside the cosmetic container appears enlarged through a Fresnel lens fitted to the outside cover. Techniques for magnifying the spine label on a box-shaped container are disclosed in British Patent Application No. GB2222143A and U.S. Pat. No. 5,366,073, according to which a cylindrical lens is arranged on one side of a compact disc (CD) case to magnify the part of the spine label facing the lens.
Furthermore, U.S. Pat. No. 5,544,741 discloses a technique by which printed information on a card inserted into a case is made visible through a side of the case. According to this technique, a window is provided on one side of the case, a prism is superposed over a printed card within the case, and information on the printed card is made visible via this prism through the window.